1. Field of Invention
The present invention relates to a precision safety ring-shaped hook, and more particularly to a unique technique for accurately guiding a locking member to open and shut a hook opening.
2. Description of Related Arts
Please refer to a safety hook disclosed in a Taiwan Patent M357531. Although it provides an improved strengthen structure, it is restricted by the structural limitation that the resistant length defined by its pivot portion 311, second pivot axle 136 and restriction portion 313 is much shorter than the force applying length defined by its locking member 31. Therefore, when the free end of the locking member 31 undertakes an external side impact stress, it fails to prevent stress being concentrated at the restriction portion 313 and the blocking portion 213, so that it fails to bear much external side impact stress. Accordingly, the restriction portion 313 and the blocking portion 213 may get loose after a long time operation.
Accordingly, the inventor of the present invention has invented the Taiwan patent M373417, entitled Safety Hook Device, which substantially improves the above drawbacks. However, the inventor does not complacent and discovers that the free end of the locking member thereof may cause interference and impaction with the hook body during the opening and shutting of the hook opening. It will cause the locking member failing to operate correctly in one time that not only increases the complication during operation, but also largely adversely affects the value of the product. Accordingly, there is a desire to improve the Taiwan patent M373417.